Adaptive Immunity: Neutralizing, Eliminating, and Remembering for the Next Time

Following viral invasion, the infected host mounts a number of responses to infection. Many of these responses involve the induction by the adaptive immune system of antibodies or cells that are specific for antigenic determinants expressed by the foreign pathogen. Infected hosts also possess a number of nonspecific defenses against an invading virus, and these have been discussed in Chapter 4, which deals with innate immunity. This chapter will first outline the key cell types involved in coordinating and mediating specific or adaptive responses to viral infections that follow initial innate immune responses. Features of the two key arms of the adaptive response, antibodies made by B cells and T cell responses, will be described. An overview will be provided of the manner by which each of these arms of the adaptive immune system mediates immunological memory and protection from re-infection. Finally, the concept of escape from adaptive immune by viruses will be introduced.